Table traversing mechanism



, @cih E?, i939. a. H. CRAMER g n TABLE TRVERSING MECHNISM Filed nec.21, 1957 s sheen-sheet 1 H/s ATTO @N5 RAYMOND H CEQA/wfg;

@et i?, i939., R. H. GRANIER TABLE TRAVERSING MECHANISM 3 Sheets-Sheet 2Filed Dec. 2l, 193'? /L//S TTO ,QA/EY C. E939. R H, GRANIER l @$175,249

TABLE TRAVERSING MEGHANISM Filed Dec. 2l, 1937 3 Sheets-Sheet 3 HAS ATTO,2A/Ef Oct. 17, 1939 -'tirarla- D STATES PATENT OFFICE I I 2,110,249 o rRaymond H. Cramer, Newark, N. J., assigner to General MotorsCorporation, Detroit, Mich., a corporation'of Delaware ApplicationDecember 21, 1937, Serial No. 181,005

Il speed of reciprocation of a table at different stages of` a cycle ofmovements. Another object is to provide improved mechanism fordeilnitely4 correlating changes in the amplitude of reciprocation withchanges in the speed. Still another Il object is to provide improvedmeans for causing table movements to` eiiect dressing of a grindingwheel. Yet another object is to provide a wheel dressing device which isso constructed as to enable the grinding spindle to have a small overnhang and a resulting stiller support.

T these ends and also to improve generally upon devices o!l thecharacter indicated, the invention consists in the various mattershereinafter desu-ibed and claimed. g In the accompanying drawings:

` Hg. 1 is a front elevation of the machine with portions in section. 1

111g. 21s an end elevation, the wheel 'head being omittdl so Fla. 3 isan end view of an indexing mecha- 4 is an end view of wiring to switchcon-` tacts.

Fig. 5 lsan axial section ofv a speed control valve.

Fl'g. 6 is a cross section on line 6--6 of Fig. 5. Fig. 'I is a wiringdiagram. Fig. 8 is a piping diagram. A Fig. 9 is a plan viewv offa wheelhead and a dressing mechanisml' v I l Fig. l0 is an end view oi Fig. 9.

Figs. 11, l2 and 13 are plan views showing different positions of thewheel and the dressing diamond with respect to the work. The numeral I 0indicates the main frame of an internal grinding machine which supportsa reciprocating table I2. Fixed to the left end of the frame is aIraised support I4 for a work head of, the chuckless type. This headcomprises a regulating wheel VI6 having a pulley Il driven by a belt 2lfrom a motor 22. The work W is supported against the regulatingy wheelby an idler wheel 20"carried by an inclined slide 26 which is adjustableby means of a screw 28. 5 vThe work is held down by a-nresure idlerwheel 16 Claims. (Cl. 51-48) 30 carried by an arm 32 secured in a block34 fastened to a rock shaft 36. Another arm 38 is secured to the rockshaft and carries an upright bracket 40 on which a gauge housing 42 isvertically adjusted by a screw 44. The bracket has 5 a lower feeler 46entering the work and supported upon its interior surface. Projectingfrom the gauge housing .is an upper feeler 48 which engages the interiorof the work and moves with respect to the lower feelcr 46 as the workchanges 10 size. The movement of the upperl feeler successively controlsa pair of electric contacts which control the time of wheel dressing andthe nal sizing of the work. The foregoing structure, in its generalaspects, is well known and is disclosed 15 in greater detail inHutchinson Patents 2,080,941 and 1,823,900.I

Mounted 'to reciprocate with the table I2 is a plate 52 carrying a crossslide 54 for a grinding wheel head 56 which has cross feeding move- 20ment under control of a feed screw 58, the feed preferably beingautomatic as the table reciprocates. A quill 60 is clamped in the headand 'supports a rotary spindle 62 having a grinding wheel G. 25

'I'he table I2 is connected to a piston rod 66 operating in a. cylinder68V mounted within the frame and controlled by a reversing valve 'I0having a rock shaft or stem 12. Pressure iluid comes' to the reversingvalve through a pipe 'I4 3o from a metering valve 16. This meteringvalve, as will later appear, has a rotary indexing member which controlsthe speed with which the pressure iluid is supplied at various times tothe reversing valve-10. A pump 18 pumps the fluid 35 from a tank througha relief valve and a pipe 60 to the center of the metering valve.Exhaust fluid returns through a pipe 82 from the reversving valve 10 tothe tank. .The stem 'I2 of the 'reversing valve can be manuallycontrolled by a 40 starting handle 84 and is automaticallyrocked by aforked arm 86 engaging a pin on a link 88 which connects the plungers oftwo solenoids and 92. v

The solenoids 90 and 92 are alternately en- 45 ergized under control oftwo switches 84 and .p86 carried by the table I2, each switch having alroller-carrying arm 88 engaging one of two oppositely extendinghorizontal arms |00 on a lever `pivoted at I 02 to the table. 'I'helever has a 50 short upwardly projecting arm |04 with a V- shaped slotwhich receives the end of a springpressed centering plunger |06. Thisplunger tends to hold the arms- |00 in a neutral position but permitsthem to be tilted when a fourth arm 55 or nger |08 is carried againstvarious stops as the table reciprocates. The stops are carried byy anindexing shaft or drum I I0 journalled in boxes ||2 on the frame. Onestop ||4 is acontinuous ring adjustably fastened to the drum by screws.The position of the stop i |4 determines the limit of the inward or lefthand stroke of the table. The drum has a plurality of longitudinalgrooves or guides iid located`90 apart. In one groove, a wheel-dressingstop H8 is adjustably secured by a screw. In two opposite grooves, stops|20 and |22 are adjustably secured, the position of these stopsdetermining the limit of the outward or right hand stroke of the tableas when the grinding wheel is making its cutting reciprocation in thework. Stop ||i may be an arm adinstable on frame l0.

The drum ii@ has an extended shaft id journalled in a bon |26 on theframe and carrying a ratchet wheel i2@ with four notches. Pivoted on theshaft is an arm |30 carryingl a pawl |32 which successively actuates theratchet wheel through arcs of 90, a spring pressed shoe |33 preventing'overrunning. A stop pin |30' limits movement of the arm in onedirection. The arm is connected by a link ist with the plunger Het ci anindexing solenoid it@ which furnishes the demng power. A coll spring |62-returns the manger. On the end of the shaft |263 is a switch arm |04having an arcuate contact plate or `wiper M5 adapted to successivelyconnect adjacent pairs of conductors at stations A, B, C and D on aninsulat plate |46 attached to the frame. See the diagram.

One of the contacts at station A is wired to one ci two co-operatingcontacts it@ in the 'eleotric gauge housing 4|.` These contacts |50 areset to complete a circuit when the work is nearly down to size and theyinstitute the wheel dressing operation. One of the contacts at station Cis Wix'edto one of two co-operating contacts |52 in the gauge housing,-these contacts being set to complete a circuit when the work isfinished. One Contact at each station is wired to the indexing solenoid|40. A contact at each of stations B and D is wired to a switch |54which is mounted on the frame and normally tends to openbut can bemomentarily closed as when its roller-carrying 'arm |56 is engaged by adog |50 which is adjustably secured to the table I2. This momenl taryclosing occurs when the tableis near the end of its inward or left-handstroke. The indexing solenoid is wired to a switch ||50which is mountedon the frame and is normally closed, this switchbeing opened only whenits roller-carrying ann |612 is engaged by adog |64 adjustably securedon the table, when such table retreatsl to its outermost position afterthe work is finished.

Fig: 1 shows the table and the finger |08 reaching the outward limit oftravel for the dressing stroke, the stbp- I8 being effective and thestop |20 having4 been indexed upwardly to an inoperative position. Inthe-usual short or grinding reciproction, the stop |20 is at the frontof the drum andthe finger |08 alternately engages the ring ||4 an'dv`the stop |20. Obviously, this vwill alternately actuate the switches 94and S|6 and alternately energize the solenoids 90 and 92 so Jthat thereversing valve stem 12 is rocked back and forth. The gauge contacts |50come together when the work is nearly to size, the rotaryv switch |'44-at that time bridging the contacts at station A. The table may then bemoving in either direction but nothing occurs until the table completesan inward stroke to momentarily close the `switch alveare 'makes anamplified stroke to the right until the ilnger |08 engages the stop H8and causes a reversal of the table. The speed of the table is slow aswill appear. On the inward stroke, the dog |50 momentarily closes theswitch |54 so that the indexing solenoid |40 is again energized. Thisswings the switch Wi to station C and indexes the shaft or drum H0 tobring the stop |22 to operative position. Thus the table resumes itsnormal working reciprocation but the speed, as will appear, is fasterthan the dressing stroke and slower than the original reciprocatlon inorder that a iine finish may be imparted to the work. When the workreaches size, the second set of gauge contacts |52 and the switch |563similarly complete a circuit so that the indexing solenoid ifi@ is againenergized and the drum turns to move the stop |22 out oi operativeposition. Thus the finger itt will meet no stop and the table will runout to the limit of its stroke, the dog itt opening the switch it@ sothat the electric circuits are broken. The rotary switch Ml then is atstation D. When the valve A72 is actuated manually by starting handle d5to send the table in again, f

the dog |56 momentarily closes switch |555 which causes another indexingmovement of the drum and brings the stop |20 to the front, the rotaryswitch then being at station A.

To produce the desired variations in speed of table reciprocation insynchronism with the above described control of the amplitude of thetable stroke, the indexing shaft or drum controls the metering valve it.The drum has a shaft extension H0 journalled in an extension of thevalve casing. Fixed to the end of the shaft within the valve casing is aplug or disc |12 having an angular port llt which successively connectsa central chamber |16 with a series of radial ports iid eachintersecting an axial port |80 in the valve body. Each port .|80intersects a conical recess |02 which opens outwardly into a circularpassage |06 which delivers pressure fluid to the pipe 74. There are fourneedle valves |86 adjustably-secured in radial positions in the valvebody. They are individually set to produce the desired speed ofreciprocation of the table for each stage of the operation. Forinstance, the diamonding stroke desirably has the slowest speed andthecorresponding needle valve would be nearly closed. The initial shortworking reciprocation would be quite fast while coarse feed grindingoccurs and the corresponding valve would be" well open. The final shortworking reciprocation should be slower to produce a good finish and thecorresponding valve would be less open. The final retreat of the tableand its initial run in can be at fast speed and the corresponding valvewould be wide open. These speeds are easily changed at any time byadjusting the valves |86.

In the usual internal grinding machine, the

dressing diamond is shifted rearwardly out of the way of the wheel headduring grinding reciprocation and is brought forward when dressing is tooccur. 'Ihe mechanism for causing this movement at the proper time hashitherto been complicated. The present invention maintains the vdressingdiamond in a forward position with provision for sliding it parallel tothe wheel axis and so makes, possible the use of a. short stubby esl:,ivme spindle which reduces the overhang of the wheel' f beyond itssupport. The wheel cannot engage the work and the diamond at the sametime. The

diamond Ill is carried on an adjusting screw II! threaded ina housing l"on a slide lll ,which is shiftabie lengthwise in an upwardly open grooveor guidewa'y il! having a cover plate 20|. 'I'he slide has a cross pin202 vhich'isconnected by a coil spring 2 to the head, the spring urgingthe,

cross pin againsta stop .20| on the h ead. Thus the slide and thediamond tend to-follow all nor- -mal sliding movements of the table andreciprocate therewith. The end of the slide is spaced lfrom a-stop screw26! secured to the frame of the gages the stop screw 2.8, and the slideand the v diamond are held from further retreat with the wheel and thetable, the coil'spring 2M then becoming elongated. As the wheelretreats, it is carried slowly across the diamond and then returns toresume .the grinding stroke. During dressing, the diamond is far enoughout from the work so that the wheel willl not engageit and the work Vatthe same time. When the wheel returns, the diamond is shifted out of theway of the quill Il and the overhang of the 'wheel spindle the quill canbe desirably short.

Figs. 9 and 11 indicatev the limits ofnormal working reciprocation ofthewheel. The vdiamond follows these movements but the slide |06.

does-'not engage the stop screw 2li until the" wheel starts to withdrawfrom the work for the dressing operation. Then the diamond stops movingand the wheel traverses slowly across it from the position shown in Fig.i2 to the position shown in Fig. 13. The stop 206 which is adjustablerecedesfrom 'the pin 202 which remains stationary until, upon the returnstroke, the stop again engages the pin and shifts the diamond away fromthe advancing quill 60 or rather keeps --the diamond in advance ofthequill.

Thus, during the grinding traverse, the diamondmaintains a relativelyxed relation to the spindle and is as close to the wheel as it can beand still avoid contact with the workor the Work holder when the wheelis at the end of its entering stroke. The quill or spindle support isclose to the diamond and closer than it could be to the grinding wheelif the diamond were fixed in the dressing position shown in Fig. 12.Accordingly, the spindle has minimum overhang from its supporting quilland the wheel has a stiff support, and yetithere is provision forlocating` the diamond in a dressing position sulciently far from thelwork so that the wheel willy not have the undesired contact with thework while the to control at least one oi the step by step movements ofthe shaft; substantially as described.

2. In a machine of the character indicated, a

beyond frame, a table.mounted to reciprocate with respect to the frame,a reversing member, a stop to engage the reversing member to determinethe limit of table travel in one direction, a shaft having a pluralityof stops movablesuccessively into operative relation to the reversingmember to change the stroke of the table in the opposite direction,ratchet mechanism for turning the shaft step by step, and means operatedby movement of the table to control one of the step by step movements ofthe shaft; substantially as described.

3. In a machine of the character lindicated, a-

frame, a table mounted to reciprocate'with respect to the frame, areversing member, a stop to engage the reversing4 member to determinethe ing a plurality o f stops movable successively into operative.relation to the reversing member to change .the stroke of thetable in'the opposite direction, ratchet mechanism for turning the" l limit oftable travel in one direction, a shaft havshaft step by step, a workgauging device con;

trolling one of the step by step movements of the shaft, and meansactuated by movement of the table for causing another step `by stepmoveA ment of the shaft; substantially as described.'

4. In a machine of the character indicated, a frame, a table mounted toreciprocate with respect to the frame, a reversing member, a stoptoengage the reversing member to determine the limit of table travel inone direction, a shaft having a plurality of stops movable successivelyinto operative relation to' the reversing member to change the stroke ofthe table in the opposite direction, ratchet mechanism for turning theshalt step by step, a solenoid for operating the ratchet mechanism, anda work gauging device and ay table operated switch for causing repeatedenergizing of the solenoid; substantially as del scribed.

5. I n a machine of the character indicated, a frame, a table mounted toreciprocate with respect to the frame, a work head on one of saidmembers and a wheel head on the other, a reversing member, strokelimiting means to engage one side of the reversing member to determinethe limit oi.' table travel in the direction causing approach of theheads, a. shaft mounted in proximity to the reversing member, stopsmounted on the shaft in angularly spaced relation and adapted to engagethe other side of the reversing member in sequence, said stops includinga spaced pair having substantially the same" longitudinal position onthe shaft and an intermediate stop having a different longitudinalposition, and means for rotating the shaft step by step to bring thethree stops successively into operative relation to the reversing memberand to finally move all of the stops out of operative vframe, a tablemounted to reciprocate with respect to the frame, power operated meansto reciprocate ythe table and comprising a. reversing valve, a rotaryshaft, stops spaced angularly and longitudinally on the shaft to operatethe reversing valve and to control changes in the amplitude of tablereciprocation, a series of' throttling valves spaced angularly withrespect to the shaft and all communicating with said reversing valve dilto control. speed of reciprocation, means on the shaft to make saidthrottling valves effective in sequence, and means for giving the shafta step by step rotation to bringv a new stop and a new throttling valveinto action; substantially as described. l

7. In a machine of the character indicated, a frame, a table mounted toreciprocate with respect to the frame, means for causing successivechanges in the amplitude of the reciprocating stroke of the table, ametering valve having a throttling member corresponding to eachamplitude, a rotary shaft having means to cause successive action of thethrottling members to change the speed of the table when the amplitudeof reciprocation is changed, ratchet mechanism for turning the shaftstep by step, and a work gauging device to control energizing oi theratchet mechanism; substantially as described.

8. In a machine of the character indicated, a frame, a table mounted toreciprocate with respect lto the frame, a metering valve having a seriesof angularly spaced throttling members to 'change the speed ofreciprocation in a series of steps, a rotary indexing shaft having meansto cause successive action of the angularly spaced throttling members,and means comprising a series of spaced stop members mounted on theshaft and directly controlled by the turning of the shaftto effectsuccessive changes in the amplitude of table reciprocation correspondingto the changing speeds; substantially as described.

9. In a machine of the character indicated, a work head, a Wheel head, aspindle projecting from the Wheel head and having a grinding.

wheel, means for -causing relative movement of reciprocation between thevWheel and the Work for grinding traverse, a dressing tool having asupporting slide shiftable with respect to the Wheel head, a spring forurging the slide to a limiting position, a stop normally spaced from theslide, and means for causing separation of the Wheel and the work, .tothereby eect engagement between the slide and the stop and a resultingtraversing engagement between the wheel and the dressing tool;substantially as described.

i0. In a machine of the character indicated, a work head, a wheel head,a spindle projecting from the Wheel head and having a grinding wheel,means for reciprocating the wheel head to traverse the wheel along theWork, a dressing tool having asupporting slide shiftabie with, and withrespect to, the wheel head, a. spring for urging ,the slide to alimiting position on the wheel head, a stop normally spaced from theslide, and means for amplifying the stroke of the wheel head to causethe slide to engage the stop and eiect traversingengagement between thewheel andthe dressing tool; substantially as p head towards the stop toretract the wheel from arras-ie reciprocation is changed tially asdescribed.

from the wheel head and having a grinding wheel to engage the Work, adressing tool adjacent to the spindle and having a supporting slideshiftable upon the wheel head, a spring urging the slide to alimitingposition on the wheel head, a stop in the path of the slide, and meansfor shifting the wheel head and the slide towards the stop to retractthe Wheel from the work and traverse the Wheel along the dressing tool;substantially as described.

,13. In a machine of the character indicated, a work head, a wheel head,a spindle projecting from the wheel head and having a grinding wheel toengage the work, a dressing tool adjacent to the spindle and having asupporting slide shifteble with, and with respect to, the Wheel head, astop normally spaced from the s lide, and means for shifting the wheelhead lto retract the wheel from the workA and to cause the slide and thestop to engage one another to eiiect a relative traversing engagementbetween the dressing tool and the wheel; substantially as described.

14. In a machine of the character indicated, a Work head, a wheel head,a spindle projecting from the head and having a grinding wheel, meansfor reciprocating the Wheel head for grinding traverse along'the work, adressing tool slidably mounted on the wheel head, means for causing thedressing tool to reciprocate with the wheel head during the grindingtraverse to keep the dressing tool out ofA contact with the Wheel head,and means to stop the reciprocating movement of the dressing tool uponan amplified stroke of the wheel head to provide for traversing theWheel across the dressing tool; substantially as described.

15. In a machine of the character described, a frame, a table mounted toreciprocate with respect to the frame, a Work head on one ci saidmembers and a tool head on the other, a reversing member, means toengage the reversing member to determine the limit o1 table travel inthe direction causing approach of the heads, a rotary indexing shafthaving a plurality of stops movable successively into operative relationto the reversing member to change the stroke of the table in thedirection causing separation of.

theheads, a plurality of speed determining members spaced angularly ofsaid indexing shaft, and a member mounted on said shaft and indexedtherewith to make said speed determining members effective in sequenceto change the speed ci tablereciprocation when the stroke ofreciprocation is changed; substantially as described.

16. In a machine of the character described,.a frame, a table mounted toreciprocate with respect to the frame, a reversing member, means toengage the reversing member to determine the limit oi table travel inone direction, a rotary indexing shaft having a. plurality oi stopsmovable successively into operative relation to the reversdit ing memberto change the stroke of the tablev in the opposite direction, aplurality of throttling members spaced angularly with respect to saidindexing shaft, and a member mounted on said y shaft and indexedtherewith to make said throttling members effective in sequence tochange the speed oftable reciprocation when the stroke of by said stops;substan- RAYMOND H. CRANER.

